Multi-Scale Analysis of Agricultural Drought Propagation on the Iberian Peninsula Using Non-Parametric Indices

Understanding how drought propagates from meteorological to agricultural drought requires further research into the combined effects of soil moisture, evapotranspiration, and precipitation, especially through the analysis of long-term data. To this end, the present study examined a multi-year reanalysis dataset (ERA5-Land) that included numerous drought events across the Iberian Peninsula, with a specific emphasis on the 2005 episode. Through this analysis, the mechanisms underlying the transition from meteorological to agricultural drought and its features for the selected region were investigated. To identify drought episodes, various non-parametric standardized drought indices were utilized. For meteorological droughts, the Standardized Precipitation-Evapotranspiration Index (SPEI) was employed, while the Standardized Soil Moisture Index (SSI), Multivariate Standardized Drought Index (MSDI), and Standard Precipitation, Evapotranspiration and Soil Moisture Index (SPESMI) were utilized for agricultural droughts, while their ability to identify relative vegetation stress in areas affected by severe droughts was investigated using the Fraction of Absorbed Photosynthetically Active Radiation (FAPAR) Anomaly provided by the Copernicus European Drought Observatory (EDO). A statistical approach based on run theory was employed to analyze several characteristics of drought propagation, such as response time scale, propagation probability, and lag time at monthly, seasonal, and six-month time scales. The retrieved response time scale was fast, about 1–2 months, and the probability of occurrence increased with the severity of the originating meteorological drought. The duration of agricultural drought was shorter than that of meteorological drought, with a delayed onset but the same term. The results obtained by multi-variate indices showed a more rapid propagation process and a tendency to identify more severe events than uni-variate indices. In general terms, agricultural indices were found to be effective in assessing vegetation stress in the Iberian Peninsula. A newly developed combined agricultural drought index was found to balance the characteristics of the other adopted indices and may be useful for future studies

Integrated sensitivity analysis of a macroscale hydrologic model in the north of the Iberian Peninsula

Process-based hydrologic models allow to identify the behavior of a basin providing a mathematical description of the hydrologic processes underlying the runoff mechanisms that govern the streamflow generation. This study focuses on a macroscale application of the Variable Infiltration Capacity (VIC) model over 31 headwater subwatersheds belonging to the Duero River Basin, located in the Iberian Peninsula, through a three-part approach: (1) the calibration and validation of the VIC model for all the subwatersheds; (2) an integrated sensitivity analysis concerning the soil parameters chosen for the calibration, and (3) an assessment of equifinality and the efficiency of the calibration algorithm. The calibration and validation processes showed good results for most of the subwatersheds in a computationally efficient way using the Shuffled-Complex-Evolution algorithm. The sensitivity measures were obtained with the Standardized Regression Coefficients method through a post-process of the outputs of a Monte Carlo simulation carried out for 10 000 parameter samples for each subwatershed. This allowed to quantify the sensitivity of the water balance components to the selected parameters for the calibration and understanding the strong dependencies between them. The final assessment of the equifinality hypothesis manifested that there are many parameter samples with performances as good as the optimum, calculated using the calibration algorithm. For almost all the analyzed subwatersheds the calibration algorithm resulted efficient, reaching the optimal fit. Both the Monte Carlo simulation and the use of a calibration algorithm will be of interest for other feasible applications of the VIC model in other river basins.Comment: Published in Journal of Hydrolog

Understanding the Drought Phenomenon in the Iberian Peninsula

The analysis and understanding of drought phenomenon are essential for the management of hydrological resources. Drought indices are commonly used to predict these extreme events, being their suitability partly due to the use of climate fields at an adequate spatiotemporal resolution. This work aims to examine spatiotemporal patterns of drought over the Iberian Peninsula (IP), which is a region especially vulnerable to drought phenomenon. For this, climate data from a simulation completed with the Weather Research and Forecasting (WRF) model have been used. The spatiotemporal patterns of drought over the period 1980–2014 were examined using the Standardized Precipitation Evapotranspiration Index (SPEI) at the 3- and the 12-month time scales, and they were compared with other drought-related variables such as the surface evapotranspiration (SFCEVP), soil moisture (SM), and runoff. The results evidence that WRF is a valuable tool for characterizing droughts over the IP, providing large amounts of climate data at an adequate spatial resolution. Drought events seem to be more severe in regard to their duration over southern IP. Moreover, a good agreement between the SPEI at 3-month time scale with the SM and the SFCEVP is found. Additionally, the annual runoff evolves similarly to the SPEI at 12-month time scale

Extreme Rainfall Indices in Southern Levant and Related Large-Scale Atmospheric Circulation Patterns: A Spatial and Temporal Analysis

This study aims to provide a comprehensive spatio-temporal analysis of the annual and seasonal extreme rainfall indices over the southern Levant from 1970 to 2020. For this, temporal and spatial trends of 15 climate extreme indices based on daily precipitation at 66 stations distributed across Israel and Palestine territories were annually and seasonally analyzed through the nonparametric Mann–Kendall test and the Sen’s slope estimator. The annual averages for frequency-based extreme indices exhibited decreasing trends, significantly for the Consecutive Dry Days. In contrast, the percentiles- and intensity-based extreme indices showed increasing trends, significant for extremely wet days, Max 1- and 3-day precipitation amount indices. The study area had expanding periods of extreme dry spells for spring and correspondingly shortening extreme wet spells for spring, winter and the combined winter–spring. Moreover, most of spring indices showed negative trends. Conversely, most winter indices displayed positive trends. Regarding the influence of large-scale circulation patterns, the North Sea Caspian pattern, the Western Mediterranean Oscillation, and ENSO were the primary regulators of the winter, spring, and autumn extreme indices, respectively. These findings contribute to a better understanding of extreme rainfall variability in the Levant region and could be utilized in the management of water resources, drought monitoring, and flood control.FEDER/Junta de Andalucia-Consejeria de Transformacion Economica, Industria, Conocimiento y Universidades P20_00035Ministry of Science and Innovation through the FEDER funds from the Spanish Pluriregional Operational Program 2014-2020 (POPE), LifeWatch-ERIC action line LifeWatch-2019-10-UGR-0

A Pareto-Based Sensitivity Analysis and Multiobjective Calibration Approach for Integrating Streamflow and Evaporation Data

Evaporation is gaining increasing attention as a calibration and evaluation variable in hydrologic studies that seek to improve the physical realism of hydrologic models and go beyond the long-established streamflow-only calibration. However, this trend is not yet reflected in sensitivity analyses aimed at determining the relevant parameters to calibrate, where streamflow has traditionally played a leading role. On the basis of a Pareto optimization approach, we propose a framework to integrate the temporal dynamics of streamflow and evaporation into the sensitivity analysis and calibration stages of the hydrologic modeling exercise, here referred to as “Pareto-based sensitivity analysis” and “multiobjective calibration.” The framework is successfully applied to a case study using the Variable Infiltration Capacity (VIC) model in three catchments located in Spain as representative of the different hydroclimatic conditions within the Iberian Peninsula. Several VIC vegetation parameters were identified as important to the performance estimates for evaporation during sensitivity analysis, and therefore were suitable candidates to improve the model representation of evaporative fluxes. Sensitivities for the streamflow performance, in turn, were mostly driven by the soil and routing parameters, with little contribution from the vegetation parameters. The multiobjective calibration experiments were carried out for the most parsimonious parameterization after a comparative analysis of the performance gains and losses for streamflow and evaporation, and yielded optimal adjustments for both hydrologic variables simultaneously. Results from this study will help to develop a better understanding of the trade-offs resulting from the joint integration of streamflow and evaporation data into modeling frameworks.ALHAMBRA cluster (http://alhambra. ugr.es) of the University of GranadaProject P20_00035, funded by the FEDER/ Junta de Andalucía-Consejería de Transformación Económica, Industria, Conocimiento y Universidades, the project CGL2017-89836-RThe Spanish Ministry of Economy and CompetitivenessEuropean Community Funds (FEDER)The project PID2021- 126401OB-I00MCIN/ AEI/10.13039/501100011033/FEDER Una manera de hacer Europa and the project LifeWatch-2019-10-UGR-01 funded by FEDER/Ministerio de Ciencia e InnovaciónThe Ministry of Education, Culture and Sport of Spain through an FPU Grant (reference FPU17/02098)Aid for Research Stays in the Hydrology and Quantitative Water Management Group of Wageningen University (reference EST19/00169)Universidad de Granada/CBU

The role of the surface evapotranspiration in regional climate modelling: Evaluation and near-term future changes

Surface evapotranspiration (SFCEVP) plays an essential role in the climate, being the link between hydrological and energy cycles. Therefore, how it is approximated and its implication in the regional climate are important aspects to understand the effects of climate change, especially in transitional zones such as the Iberian Peninsula (IP). This study aims to investigate the spatiotemporal patterns of the SFCEVP using a regional climate model (RCM), the Weather Research and Forecasting (WRF) model. To this purpose, a set of WRF simulations were completed using different driving data. On the first hand, a recent present (1980–2017) simulation driven by the ERA-Interim reanalysis was carried out to evaluate the suitability of the RCM performance. On the other hand, two global climate models (GCMs) from the CMIP5 initiative, the CESM1 and the MPI-ESM-LR, were used as driving data to evaluate the GCM-RCM coupling, which is essential to climate change applications. Finally, projected changes were also investigated for a near-term future (2021–2050) paradigm. In general, the results pointed out the WRF model as a valuable tool to study the spatiotemporal patterns of the SFCEVP in the IP, showing an overall and acceptable ability at different spatial and temporal scales. Concerning projections, the results indicate that the IP is likely to undergo significant changes in the SFCEVP in the near future. These changes will be more apparent over the southernmost, and particularly during spring and summer, being in the latter season the SFCEVP fundamentally reduced. These results agree with projected changes in soil moisture, which is probably associated with changes in precipitation patterns. Additionally, the results reveal the major role of SFCEVP in modulating the climate over this region, which is involved in the complex land-atmosphere processes.Departamento de Física Aplicada, Facultad de Ciencias, Universidad de Granad

Projected hydrologic changes over the north of the Iberian Peninsula using a Euro-CORDEX multi-model ensemble

This study explores the impacts of climate change on the hydrology of the headwater areas of the Duero River Basin, the largest basin of the Iberian Peninsula. To this end, an ensemble of 18 Euro-CORDEX model experiments was gathered for two periods, 1975–2005 and 2021–2100, under two Representative Concentration Pathways (RCP4.5 and RCP8.5), and were used as the meteorological forcings of the Variable Infiltration Capacity (VIC) during the hydrological modelling exercise. The projected hydrologic changes for the future period were analyzed at annual and seasonal scales using several evaluation metrics, such as the delta changes of the atmospheric and land variables, the runoff and evapotranspiration ratios of the overall water balance, the snowmelt contribution to the total streamflow and the centroid position for the daily hydrograph of the average hydrologic year. Annual streamflow reductions of up to 40% were attained in various parts of the basin for the period 2071–2100 under the RCP8.5 scenario, and resulted from the precipitation decreases in the southern subwatersheds and the combined effect of the precipitation decreases and evapotranspiration increases in the north. The runoff and the evapotranspiration ratios evinced a tendency towards an evaporative regime in the north part of the basin and a strengthening of the evaporative response in the south. Seasonal streamflow changes were mostly negative and dependent on the season considered, with greater detriments in spring and summer, and less intense ones in autumn and winter. The snowmelt contribution to the total streamflow was strongly diminished with decreases reaching −80% in autumn and spring, thus pointing to a change in the snow regime for the Duero mountains. Finally, the annual and seasonal changes of the centroid position accounted for the shape changes of the hydrograph, constituting a measure of seasonality and reflecting high correlations degrees with the streamflow delta changes.Departamento Física Aplicada, Facultad de Ciencias, Universidad de GranadaSpanish Ministry of Economy and625 Competitiveness projects CGL2013-48539-R and CGL2017-89836-REuropean Community Funds (FEDER) and by FEDER/Junta de Andalucía-Consejería627 de Economía y Conocimiento/B-RNM-336-UGR18 projectMinistry of Education, Culture and Sport of Spain (FPU grant FPU17/02098

Daily gridded datasets of snow depth and snow water equivalent for the Iberian Peninsula from 1980 to 2014

We present snow observations and a validated daily gridded snowpack dataset that was simulated from downscaled reanalysis of data for the Iberian Peninsula. The Iberian Peninsula has long-lasting seasonal snowpacks in its different mountain ranges, and winter snowfall occurs in most of its area. However, there are only limited direct observations of snow depth (SD) and snow water equivalent (SWE), making it difficult to analyze snow dynamics and the spatiotemporal patterns of snowfall. We used meteorological data from downscaled reanalyses as input of a physically based snow energy balance model to simulate SWE and SD over the Iberian Peninsula from 1980 to 2014. More specifically, the ERA-Interim reanalysis was downscaled to 10 km 10 km resolution using the Weather Research and Forecasting (WRF) model. The WRF outputs were used directly, or as input to other submodels, to obtain data needed to drive the Factorial Snow Model (FSM). We used lapse rate coefficients and hygrobarometric adjustments to simulate snow series at 100m elevations bands for each 10 km 10 km grid cell in the Iberian Peninsula. The snow series were validated using data from MODIS satellite sensor and ground observations. The overall simulated snow series accurately reproduced the interannual variability of snowpack and the spatial variability of snow accumulation and melting, even in very complex topographic terrains. Thus, the presented dataset may be useful for many applications, including land management, hydrometeorological studies, phenology of flora and fauna, winter tourism, and risk management. The data presented here are freely available for download from Zenodo (https://doi.org/10.5281/zenodo.854618). This paper fully describes the work flow, data validation, uncertainty assessment, and possible applications and limitations of the database.Esteban Alonso-González is supported by the Spanish Ministry of Economy and Competitiveness (BES- 2015-071466). This study was funded by the Spanish Ministry of Economy and Competitiveness projects CGL2014-52599-P 10 (Estudio del manto de nieve en la montaña española y su respuesta a la variabilidad y cambio climatico) and CGL2017- 82216-R (HIDROIBERNIEVE) and (with additional support from the European Community funds, FEDER) CGL2013-48539-R (Impactos del cambio climático en los recursos hídricos de la cuenca del Duero a alta resolución). Also, the Regional Government of Andalusia has funded this research with the project P11-RNM-7941 (Impactos del Cambio Climático en la cuenca del Guadalquivir, LICUA)

Emergencia del cambio climático en cuencas de la Península Ibérica

Ponencia presentada en: XII Congreso de la Asociación Española de Climatología celebrado en Santiago de Compostela entre el 19 y el 21 de octubre de 2022.[ES]Se espera que el aumento de la concentración de gases de efecto invernadero (GEI) a la atmósfera cause importantes cambios en el sistema climático. Sin embargo, cómo será dicho efecto en el comportamiento de las diferentes variables climáticas es aún incierto a escala regional. Este estudio investiga la potencial emergencia de la señal de cambio climático antropogénico para las diferentes cuencas hidrográficas de la Península Ibérica (PI), una región especialmente vulnerable a los efectos del cambio climático. Para ello se analizan proyecciones de cambio climático regional de temperatura y precipitación a partir de la relación señal/ruido (S/N) calculada a escala estacional. Dichas proyecciones se obtuvieron con el modelo Weather Research and Forecasting (WRF) el cual fue conducido por el modelo climático global (GCM) MPI-ESM-LR. MPI-ESM-LR fue previamente corregido en sesgo para simular el clima en la PI en el periodo de 1980 a 2100 bajo dos escenarios de emisión, el RCP4.5 y el RCP8.5. En general, los resultados mostraron que la señal de cambio climático antropogénico es probable que emerja durante el siglo XXI, al menos para la temperatura, siendo dicha señal más fuerte bajo el escenario RCP8.5 durante el otoño y verano. Bajo este mismo escenario, la precipitación muestra una señal de cambio más fuerte en primavera y verano. Determinar cómo evolucionará la señal de cambio antropogénica y cuando emergerá es de vital importancia, por lo que estos resultados pueden ayudar a la toma de decisiones y a la implementación de políticas de prevención y adaptación al cambio climático adecuadas.[EN]The rising concentration of greenhouse gases (GHGs) to the atmosphere is expected to cause significant changes in the climate system. However, it is still uncertain how this factor would affect the behavior of different climatic variables on a regional scale.This study explores the potential emergence of the signal of anthropogenic climate change for the different river basins in the Iberian Peninsula (IP), a region that is especially vulnerable to the effects of climate change. For this purpose, regional climate change projections of precipitation and temperature were analyzed by means of the signal-to-noise (S/N) ratio at a seasonal scale. These projections were achieved with the Weather Research and Forecasting (WRF) model, which was driven by the MPI-ESM-LR global climate model (GCM). MPI-ESM-LR was previously corrected in bias to simulate the climate in the IP for the period 1979 to 2100 under two emission scenarios, RCP4.5 and RCP8.5.Overall, the results indicated that the anthropogenic climate change signal is likely to emerge over the twenty-first century, at least for temperature, with this signal being stronger under the RCP8.5 scenario during autumn and summer. Under this same scenario, precipitation shows a stronger signal in summer and spring. Determining how the anthropogenic change signal will evolve and when it will emerge is critical; as a result, these findings can assist decision makers in developing appropriate adaptation and mitigation policies to climate change.Este estudio ha sido financiado por FEDER/Junta de Andalucía-Consejería de Transformación Económica, Industria, Conocimiento y Universidades (proyecto P20_00035), Ministerio de Ciencia e Innovación (proyecto LifeWatch-2019-10-UGR-01), FEDER/Junta de Andalucía-Consejería de Economía y Conocimiento (proyecto B-RNM-336-UGR18), y Ministerio de Economía, Industria y Competitividad (proyecto CGL2017-89836-R)

Estudio de la habilidad de las predicciones climáticas decenales para reproducir patrones de circulación atmosférica de gran escala

Ponencia presentada en: XII Congreso de la Asociación Española de Climatología celebrado en Santiago de Compostela entre el 19 y el 21 de octubre de 2022.[ES]El objetivo de este trabajo es evaluar la capacidad del Decadal Prediction Large Ensemble (DPLE) para reproducir los principales patrones de circulación atmosférica del hemisferio norte. El DPLE está constituido por una serie de simulaciones climáticas decenales llevadas a cabo con el Community Earth System Model (CESM) e inicializadas cada año en noviembre desde 1954 hasta 2015. Para cada fecha de inicialización, un total de 40 realizaciones fueron generadas mediante la perturbación aleatoria de las condiciones iniciales atmosféricas. En este estudio se han analizado los principales modos de variabilidad espaciotemporal en invierno (diciembre, enero y febrero) de la presión a nivel del mar (SLP) del DPLE mediante un análisis de componentes principales (PCA). Se ha tomado como referencia la SLP del reanálisis del Japanese 55-year Reanalysis (JRA-55) en la evaluación de los resultados. La mayor correspondencia entre los modos de variabilidad del DPLE y los de referencia se da para el rango de predicción de 1-4 años, aunque las correlaciones existentes entre las componentes principales rotadas no superan el valor de 0.5. Las correlaciones disminuyen para los rangos de predicción de 3-6 y 6-9 años.[EN]The aim of this study is to evaluate the skill of Decadal Prediction Large Ensemble (DPLE) in reproducing the main atmospheric circulation patterns in the Northern Hemisphere. The DPLE encompasses a collection of near-term climate simulations carried out with the Community Earth System Model (CESM) and initialised every year in November from 1954 to 2015. For each initial date, an ensemble of 40 members was generated by randomly perturbing the initial atmospheric conditions. In this study, the main spatio-temporal variability modes of DPLE sea level pressure (SLP) in winter (December, January, and February) have been analysed by means of a principal component analysis (PCA). SLP data from the Japanese 55-year Reanalysis (JRA-55) has been used as a reference dataset in the evaluation of the results. The largest similarities between the DPLE and reference variability modes have been found in the forecast range of 1-4 years, although the correlations between the rotated principal components do not surpass 0.5. The correlations decrease for the forecast ranges of 3-6 and 6-9 years.Este estudio ha sido realizado en el marco del proyecto CGL2017-89836-R, financiado por el Ministerio de Economía y Competitividad, y con fondos FEDER adicionales: B-RNM-336- UGR18, financiado por FEDER/Junta de Andalucía - Conserjería de Economía y Conocimiento, y P20_00035, financiado por FEDER/Junta de Andalucía-Conserjería de Transformación Económica, Industria, Conocimiento y Universidades, y Ministerio de Ciencia e Innovación (proyecto LifeWatch-2019-10-UGR-01)